A unique method by which to quantitate synchrony with equilibrium radionuclide angiography

• Published in: Journal of nuclear cardiology 2005-07, Vol.12 (4), p.441-450
• Main Authors: O’Connell, J. William, Schreck, Carole, Moles, Michael, Badwar, Nitish, DeMarco, Theresa, Olgin, Jeffrey, Lee, Byron, Tseng, Zian, Kumar, Uday, Botvinick, Elias H.
• Format: Article
• Language: English
• Subjects: Adult; Aged; Cardiac Pacing, Artificial - methods; Female; Gated Blood-Pool Imaging - methods; Heart attacks; Heart Conduction System; Heart failure; Humans; Image Interpretation, Computer-Assisted - methods; Male; Medical imaging; Myocardial Contraction; Prognosis; Severity of Illness Index; Treatment Outcome; Ventricular Dysfunction, Left - diagnostic imaging; Ventricular Dysfunction, Left - therapy
• ISSN: 1071-3581; 1532-6551
• DOI: 10.1016/j.nuclcard.2005.05.006

Cardiac resynchronization therapy (CRT) improves symptoms and the survival rate in patients with advanced heart failure by improving synchrony. However, CRT is not always successful, is costly, and is applied without individualization. There is no specific measure of synchrony. The goal of this study was to analyze new quantitative parameters of synchrony and compare them with established measures. Equilibrium radionuclide angiography, phase angle (Ø), and amplitude quantitate regional contraction timing and magnitude and are the basis for new synchrony ( S) and entropy ( E) parameters. S is the vector sum of all amplitudes based on the angular distribution of Ø divided by the scalar sum of the length of all vectors. Complete S equals 1, and its absence equals 0. E measures the disorder in the region of interest, is 1 with random contraction and 0 with full synchrony, and differentiates among differing contraction patterns. Left ventricular S and E were measured in 22 normal equilibrium radionuclide angiography studies, where regions of interest were drawn from the left ventricle, left atrium, and background to analyze model ventricles with normal wall motion (N), ventricles with aneurysm (An), ventricles with severe diffuse dysfunction (Diff), and ventricles with severe regional dysfunction (Reg). The new S and E parameters were highly reproducible and well differentiated among N, An, Diff, and Reg, which were not separated by SD Ø (SD of ventricular phase), which has gained popularity as a measure of synchrony. Unique scintigraphic parameters for the evaluation of ventricular synchrony were derived, and their added value was determine compared with established measures. Indications for pacemaker therapy now include the treatment of severe congestive heart failure (CHF). Atrial triggered biventricular pacemakers reduce CHF symptoms 1 and prolong life 2 in patients with cardiomyopathy, severe CHF, left ventricular (LV) ejection fraction (EF) lower than 35%, and QRS greater than 120 milliseconds. Such pacing, or cardiac resynchronization therapy (CRT), seeks to reduce the heterogeneity and increase the synchrony of ventricular activation, conduction, and contraction. CRT has improved hemodynamics, increased exercise tolerance, reduced symptoms and the need for hospitalization, 1,3 reversed ventricular remodeling, 4,5 and reduced the all-cause mortality rate 2 in CHF. However, CRT is costly, fails to improve symptoms or activity level in more than 30% of pat